Automatic telephone system



Dec. 6, 1955 F. KESSLER E L 2,726,234

AUTOMATIC TELEPHONE SYSTEM Original Filed Sept. 15, 1949 13 Sheets-Sheet l CONN. BANK T R 8 LI NE Fl N DER LINE CCT.

NOTES I. WIRE HSW IS CONNECTED THROUGH A RESISTANCE TO I") IN TOLL TRUNK CIRCUIT WHEN II IMPULSE IS TRANSMITTEO.

HSW FHS 0 FIG XX TX LBT\ AST INVENTORS,

FRANK KESSLER BY WILLIAM w. PHARIS ATTORNEY Dec. 6, 1955 F. KESSLER ET AL 2,726,284

AUTOMATIC TELEPHONE SYSTEM Original Filed Sept. 13, 1949- 13 Sheets-Sheet 2 l I 1 Fl 6. 2 wwli l l 22 I INVENTORS.

FRANK KESSLER WILLIAM W. PHARIS BYJfZ ATTORNEY Dec. 6, 1955 F. KESSLER ET AL AUTOMATIC TELEPHONE SYSTEM 13 Sheets-Sheet 3 Original Filed Sept. 15, 1949 LINE FINDER THS FIG. 3

INVENTORS. FRANK KESSLER By WILLIAM w. PHARIS PG ,IALG

ATTORNEY Dec. 6, 1955 F. KESSLER ET AL 2,726,284

AUTOMATIC TELEPHONE SYSTEM Original Filed Sept. 15, 1949 15 SheetsSheet 5 BUSY TONE DIAL TONE SELECTOR CERTAIN LEVELS T F 3XYOF I n I I I HS I I I I H1 1 i I I I I I I I l I I i I I 1 I I I l I I S C S I Iv 3YON 3XON NOTE IF men CANCELLING N I F T IS REQUIRED ON I I I CONNECT W TO LEVELS REQUIRING DIGIT CANCELLING AND CONNECT M TO IXON : LEVELS NOT REQUIR- I I I ING DIGIT CANCELLING L I E t ZXON q f INVENTORS. FRANK KESSLER 5 WILLIAM W. PHARIS ATTORNEY Dec. 6, 1955 F. KESSLER ET AL 2,726,234

AUTOMATIC TELEPHONE SYSTEM Original Filed Sept. 13, 1949 13 Sheets-Sheet 6 CON NECTOR INVENTORS.

FRANK KESSLER WILLIAM W. PHARIS ATTORNEY FIG. 6

Dec. 6, 1955 F. KESSLER ET L AUTOMATIC TELEPHONE SYSTEM 13 Sheets-Sheet 7 Original Filed Sept. 13, 1949 u m W m m m f E J H w I w Y III l I I I I I I I I I IIIIIIIIIIIIIIII 3 2 I 6 u X m... Ir J I I I I I I I I I I I N J F. X 3 m S l H R\ I I I I I I I PM I I I V V I H I I I I I I I I I I I I A T I I I I I W I I I I I I Em R O T R 7 I I I I I I I I I I I I I I I I I I I I I I I N I N m 0 F. C V

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FIG. II

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FIG. 9

FIG. 6

FIG. 7

FIG. 5

FIG. 3

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FIG. 2

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ATTORNEY Dec. 6, 1955 F. KESSLER ET AL 2,726,284

AUTOMATIC TELEPHONE SYSTEM Original Filed Sept. 13, 1949 13 Sheets-Sheet 8 co N N ECTOR 31 m1 32 A T32 INVENTORS.

FRANK KESSLER WILLIAM W. PHARIS 8 ATTORNEY Dec. 6, 1955 ss ET AL AUTOMATIC TELEPHONE SYSTEM 13 Sheets-Sheet 9 Original Filed Sept. 13, 1949 W OPERATE CON N ECTOR FIG. 9

INVENTORS. FRANK KESSLER WILLIAM W. PHARlS ATTORNEY Dec. 6, 1955 F. KESSLER ET AL AUTOMATIC TELEPHONE SYSTEM 15 Sheets-Sheet 10 Original Filed Sept. 13. 1949 INVENTORS. FRANK KESSLER WILLIAM w. PHARIS DIAL TONE 34 CONNECTOR FIG. IO

ATTORNEY Dec. 6, 1955 F. KESSLER ET AL 2,726,284

AUTOMATIC TELEPHONE SYSTEM Original Filed Sept. 15, 1949 I 13 Sheets-Sheet ll ZMON CON N ECTOR FIG. II

INVENTORS. FRANK KESSLER WILLIAM W. PHARIS B ATTORNEY Dec. 6, 1955 F. KESSLER ET AL AUTOMATIC TELEPHONE SYSTEM 13 Sheets-Sheet 12 Original Filed Sept. 13, 1949 ATTORNEY TONE CON N ECTOR YFIG. I2

Dec. 6, 1955 F. KESSLER ET AL 2,726,284

AUTOMATIC TELEPHONE SYSTEM Original Filed Sept. 13, 1949 13 Sheets-Sheet l3 NOTES I. FIRST LINE OF P.B.X.GROUP HAS HS TERMINAL CONNECTED TO (H 2. LAST LINE OF P.B.X. GROUP HAS HS AND S TERMINALS CONNECTED TOGETHER I I I28-I 38 I23 I ,I24 I27 CA (-I I I (-I I I HI I I 1 I I) 96 I I X I I I I I I- II MI I I I I I l I I00 I I f 1 I -I------.-I CWT I I IXON I I r--7- MG I I I L I l I TO GEN. SOURCES \IOI I I I I GEN N fi I I I I IIIIIIIIIII IIYON I I05 I I40 I I I I I39 I I I I l I INTC I06 I I I r-QOOQOOOQOOO I l I I0? I I I I RV I I I I 3 5 7 9 I EII1I I l2l4IIsIelo DE I I I II I I I I I f I I I38 I I CONNECTOR IMON F I G I 3 INVENTORS.

FRANK KESSLER WILLIAM Ww PHARIS BY \ZXM ATTORNEY United States Patent C) AUTOMATIC TELEPHONE SYSTEM Frank Kessler, Los Angeles, Calif., vand William W.

Pharis, Rochester, N. Y., assignors, by mesne assignments, to General Dynamics Corporation, a corporation of Delaware 1 Original application September 13, 1949, Serial N0. 115,392. Divided and this application October 18, 1951, Serial No. 251,962

5 Claims. (Cl. 179-18) This invention relates to telephone systems and it more particularly pertains to automatic telephone systems using step by step switches.

The present application is a division of our copending application Serial No. 115,392, filed September 13, 1949, now Patent 2,668,194, issued February 2, 1954.

It is the main object of the present invention to provide improved circuits, of the character later described, which render the equipment simple and economical and which function in a positive and reliable manner to provide dial service in a telephone exchange.

For the purpose of simplifying the illustrations and facilitating the explanation, various parts and circuits constituting the embodiment of the invention have been shown diagrammatically and certain conventional illustrations have been employed, the drawings havingbeen made more with the purpose of making it easy to understand the principles and mode of operation than with the idea of illustrating the specific construction and arran'gement of parts that would be actually employed in practice. For example, the various relays and their contacts are illustrated in a conventional manner, with all of the contacts controlled by a particular relay being associated with this relay by means of a dashed line. Instead of making use of the usual battery and ground connections usually found in telephone circuits, it has been found convenient to indicate the connections to the negative side of the common battery by the symbol and to illustrate the connections to the positive or ground terminal of the battery by means of the symbol, it being understood that these corresponding symbols on all of the drawings in the present disclosure connect to the same terminals of the common source of current.

It is an object of the invention to provide a telephone system having an improved connector circuit of universal application with simplified means to control the extension of ringing current for either toll or local calls.

Another object of the present invention. is the provision of a lock pulse arrangement in the selector and in the connector, whereby an impulse repeating relay is controlled by the usual impulse relay which responds to impulses in the line circuit, this additional impulse repeating relay being arranged to operate when the usual impulse relay releases, locks itself operated, control the stepping operation of the associated selector switch, after which its locking circuit is opened and the relay is released when the line impulse relay next operates. In other words the impulse repeating relay is operated in response to an impulse and remains operated for energizing the stepping magnet until said magnet is actually operated. I

The novel features believed to be characteristic of the invention are set forth in the appended claims, The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the folpanying drawings in which like characters designate corresponding parts and in which:

Fig. 14 is a block diagram showing how the other fig tioned line finder.

lowing specification taken in connection with the accom- Fig. 5 shows the apparatus and circuits of the selector associated with the above mentioned line finder to make up one link circuit.

Figs. 2 and 4 show the circuits and apparatus of the common allotter used in connection. with the allotment of the finder-selector links of the system.

Figs. 6 to 13, inclusive, show the circuits and apparatus of a typical connector used in the system of the present embodiment, with the minor switch which is associated with the connector being shown in Fig. 13.

It is believed that the operation of the system, together with the features disclosed, will best be understood by describing a typical call originated on the line circuit of Fig. 1 and extending to a connector terminal, illustrated in Fig. 12 and indicated to called line, assuming that the calling line number is 33 and that the called line designation is 2222.

Line, line finder and allotter operation When the receiver is removed at the calling station, the closed circuit across the calling line efiects the operation of the line relay LR of the associated line circuit, this circuit being traced from upper winding of line relay LR, break contact of cut off relay CO, upper side of the calling line T and the substation in series, lower side of the calling line R, break contact of relay CO, lower winding of relay LR, break contact of lockout relay LO, common link busy tone conductor LBT and upper winding of tone transformer TTF to The operation of relay LR immediately makes this line busy by applying to sleeve conductor S leading to they connector banks. The operation of relay LR also marks the levelin which the calling line is located by applying (-1-) by way of the lowermost make contact of relay LR and break contact of relay L0 to the third oif normal level terminal in the XX bank of the line finder. The= operation of relay LR also marks the terminal in thelevel associated with the calling line by applying to the terminal of brush P8 of the finder over a circuit which may be traced from Winding of relay LO,

winding ofrelay CO, make contact of relay LR and the terminal to which wiper P8 of the finder makescontact.

The operation of relay LR closes a circuit for operating start relay ST of the allotter extending from lowermost make contact of relay LR, break contact of relay LQ, resistor lRS, common start conductor AST and windingof start relay ST of the allotter to The operation of relay ST closes a circuit for operatingrelay SA of the associated allotter which may be traced from break contact of relayLS, conductor 11, make contact of relay ST, break contact of relay XB, break closed for operating relay ST ofthe allotted line finder j which may be traced from make contact of relay SA, break contact of relay RS, conductor 12, make contact of relay lAL, conductor IFST, break contact of relay SW'and winding of relay ST to With either relay Patented Dec. 6, 1955 ST of relay SA of the allotter operated, the common start conductor is energized for staffing the mechanism which provides timed pulses on the common timing conductors for a purpose which will be later described. It will be noted that relay 1AL is' locked operated over a circuit extending from make contact of relay lAL, conductor lAL, break contact of relay SW, X oif normal contact XON and Y off normal contact YON of the line finder, conductor 1ALG and lower winding of relay 1AL to The operation of relay ST of the line finder closes a bridge around the X and Y oif normal contacts to maintain this locking circuit for relay lAL complete even while the line finder is operated in its X and Y directions. v, u

The pulsing relays PA and PB of the allotter are now started operating by means of a circuit on pulse conduct'or PG' extending from make contact of relay ST of the line finder, conductor PG, make contact of relay 1A1, break contact of relay LS, conductor 13, break contact of relay YS, break contacts of relay PA to the operating windings of relays PA and PB to At the same time that this circuit is closed, another circuit from this same extends through the lower winding of relay PA and condenser lCN to H Before this circuit is closed by way of conductor PG, condenser ICN is charged over a circuit including both windings in series of relay PA. Now when is applied to the PG conductor, the condenser discharges through the lower winding of relay PA in such a direction that the current flow through this lower winding opposes that through the upper winding, this resulting in the slow operation of relay PA, the time of operation of this relay being determined by the time of discharge of the condenser. Relay PB of course operates before relay PA.

When relay PA operates, the above described circuit for relay PBis opened and this latter relay releases. It is slightly slow to release because of resistor 9R8 bridged a'cro'ss'its winding. The'operation of relay PA also opens up the above described circuit to its own winding for elfecting the release of this relay. Relay PA is slow to releaseafter its upper winding is de-energized because of the charge current for condenser lCN which'now flows through both windings of relay PA in series aiding relation, thus holding this relayoperated until the charge cycle of the condenser reaches a predetermined point} Relay PA is also slowed up in its'release by resistor IORS.

When relay PA releases; theabove described circuits'fo i" thisrelay and the PB relay' are; again closedand these relays repeat the aboye described cycle. This continues with relays PA and PB pumpingalong to provide'piilse's' for operating magnet X of the line finderio'ver a'circiiit' which'will now be described. Each time relay PB o erates, a circuit is closed for operating the X magnet of the allotted finder traced from break contact of relay LS, break contact of relay AS, conductor 14, make contact of relay SA, make contact of relay PB,Ibreak contact of relay XB, conductor 15, make contact of relay lAL, conductor XMand winding of m'agnet'X to When the marked level is reachedbythe linefinder (level 3 in this example) a circuit is closed for the'IX magnet stop relay XA in the allotter which may be traced from make contact of relay LR of the linelcir'cuit, break contact of relay LO; terminal and wiper XX of the operating line finder, conductor 5, X stop conductor 'XSP, make contact of relay 1AL of the allotter, break contact of relay AS, conductor 16, break contact'of' relay YA and lower winding of relay XA to Relay XA closes.

a locking circuit for itself extending'fi'oin break contacts in series of relays LS, and'AS,:.'condi1ctor.14, makecontact of relay SA, makefcontact aiid u pper 'windmg of relay XA to Whenrelay'XA operatesfa substitute circuit'is'closed for relay'SAwhich is' inde:

pendent of the previously described circuit including conductor 11, this substitute circuit'ext'ending-from break contact of relay LS, conductor '17, break contact of relay YS, make contactpf relay XA and winding of relay SA to Thisoperation of relay XA occurs during the time that relay PB is operated for stepping the finder switch to the marked level and during the time that relay PA is operated for efifecting the release of relay PB. Now when relay PB releases, a circuit is closed for operating relay XB of the allotter extending from break contacts in series of relays LS and AS, conductor 14, make contact of relay SA, break contact of relay PB, make contact of relay XA, break contact and winding of relay XB to Relay XB closes a locking circuit for itself extending from the above described circuit including conductor 14, make contact of relay SA, resistor 3RS, make contact and winding of relay XB to When relay PB operates the next time it does not close a circuit to the X magnet of the line finder because this circuit, including conductor 15, is open at the break contact of relay XB. This operationofi relay PB does close a circuit, however, for relay YA which may be traced from on conductor 14, make contact of relay SA, make contact of relay PB, make contact of relay XB, break contact of relay YB and winding of relay YA to When relay PB is next released a. circuit is closed for operating rclay YB and for lockingr elay YA, this circuit being traced from on conductor 14, make contact of relay SA, winding of relay YB, make contact and winding of relay YA to This circuit is effective because the release of relay PB opens up the circuit extending by way of the lower break contact of 'relay YB to the winding of relay YA" for removing the short circuit from the winding of relay YB, thus permitting the operation of this latter relay'in series with the winding. of relay YA. This operation of the XA, XB, YA and YB relays measures off a time interval after the primary or X magnet of the line finder hascompleted its operation and before the circuit i'sclosed for operating the Y magnet of this finder, thus permitting the wipers of the finder to stop vibrating before entering the bank of the selected level.

The next operationof relay. PB, after relay YB has beenoperated, closes a circuit for operating the secondary or Y magnet of the allotted finder, extending from ddconductor 14, make contact of relay SA, make contact or relay PB, make contact of relay XB,, make contact of relayYB, conductor 18, make contact of relay 1AL, conductor YM and windingotmagnet Y to When relay PB releases, this circuit to, the line finder Y magnet is opened for effecting the, release of this magnet, thus stoppingthe switch at the terminal in the level. Now when relay PB isnext operated, ,the above mentioned circuit to the Y magnet is again closedifor stepping the line finder tovthe second terminal in the level, after which relay PB' is released. Thefinder is stepped to the third terminal in thelevelwhen relay PB again operates for closing the above described circuit to the Y magnet. Now when relay PB releases, the Y magnet is de-energized leaving the switch at the third terminal in the third level.

Referring back to the operation of relay YB of the allotter, a priming circuit isiclosed for, Y stop relay YS to 'co'ndition this relay for fastoperation when the marked terminal is reached, forstopping the line finder Y stepping operation. Thisprimingcircuit may be traced from make contact of relay YB, resistor 7RS and upper winding of relay Y S to When the line finder reaches the marked, terminal a circuit is closed for operating relay YSof the allotter which maybe traced from on conductor 14, make contact of relay SA, lower windingof relayY S; make contact of reiay Y'A, Y- stop conductorYSP, break contact of relay SW of the line tinder. make contact of relay, ST,; conductor ii, finder switch sleeve wiper F'Sand its. associated terminal, makexcontact 0t relay LR- of the linelcircuit, windings of relays CO and LO iniserieslto This circuit, in, addition to operating relay Y S, operatesrelays CO and 1.0 of the line circuit. The operation 0t relay CQ opens up and releases" relay LR, but before this latter relay is released a locking circuit is closed for relays CO and LO including the lowermost make contact of relay C0, this contact bridging the make contact of relay LR.

The operation of relay'YS of the allotter opens up the above described operating circuit to the PA and PB relays for stopping the operation of these pulsing relays. To prevent the premature release of relay PB, the operation of relay YS closes a locking circuit for relay PB which may be traced from make contact of relay STof the line finder, conductor PG, make contact of relay 1AL, break contact of relay LS, conductor 13, make contact of relay YS, make contact and winding of relay PB to The operation of relay YS opens up the above described circuit for relay SA for elfecting the release of this relay. The release of relay SA closes a circuit for operating relay SW of the line finder which may be traced from coming back over sleeve conductor TS from a make contact of relay RD of the selector (the CB and RD relays of the selector being operated early in the cycle as will be later explained), break contact of magnet Z, make contact of relay ST, X and Y ofl normal contacts in multiple, lower winding of relay SW and winding of relay ST to This circuit is eifective because conductor lFST is disconnected from by the release of relay SA, thus removing the short circuit from the lower winding of relay SW and allowing this relay to operate in series with the winding of relay ST in a locking circuit for this latter relay previously described. With relays SW and ST of the line finder operated, coming back over conductor TS from the selector is extended through make contacts of these two relays, conductor 3, wiper FS and terminal of the line finder for holding relays CO and LO of the line circuit. The release of relay SA disconnects conductor 14 from the windings of relays YS, XA, XB, YA and YB for effecting the release of these relays. During the short interval that relay YS was operated, a circuit was closed for operating peg count meter PC for counting this call. This circuit may be traced from break contact of relay LS, conductor 17, make contact of relay YS and winding of meter PC to The operation of relay LO of the line finder opens up the circuit including conductor AST for effecting the release of relay ST in the event that there is no other call waiting. In the case of simultaneous calls, relay ST remains operated and when relays XA and XB release, relay SA can again operate. This operates relay ST of the next finder for running the circuits through another cycle in the same manner just described. The operation of relay SW of the line finder opens up conductor 1AL for opening up the above described locking circuit for relay 1AL for effecting the release of this relay. This allots the next link for the next call and relay 1AL cannot again operate until an allotting period is efiected as will be later described. The circuit for operating the pulse generating relays PA and PG, including conductor PG, is opened by the release of relay 1AL so that the pulse generating relays will not be operated when relay YS releases to connect conductor 13 to these pulse generating relays.

It will now be explained how a so-called allotting period is effected for reconditioning the allotter relays lAL- AL of links which have become idle, this reconditioning being efiective only when all links of the group have been used, i. e., full rotation of the links provided. It will be assumed that, previous to the release of relay lAL as above described, all other AL relays associated with other finder links were released because of the use of these finder links. It will also be assumed that in the meantime links 2, 6 and 10 have become idle. It now'becomes necessary to effect an allotting period operation for operating the AL relays associated with these idle links in order that these links may be used by succeeding calls. With all AL relays released, a series circuit is extended through the break contacts of all of these relays from (jon the sixth spring combination from 6 the top of relay lAL, through similar break contacts of all other AL relays, including relay 10AL, conductor 19 and lower winding of relay RS to Thisseries.

with these links and the lower windings of the AL relays over a circuit which is similar to that shown from conductor lALG leading to the lower winding of the 1AL relay. This operates the 2, 6 and 10AL relays and then a locking circuit is closed for these relays which includes the AL and ALG conductors and the lower windings of the associated AL relays to When all of these AL relays have been operated, the above described locking circuit for relay RS, including its upper winding, is opened for efiecting the slow release of relay RS. This marks the end of the allotting period and since the AL relays associated with idle links have been operated, these links may be taken for use in the previously described manner. While relay RS is in its operated position a tone is connected back to tone transformer TTF so that a calling party will receive this tone by way of the line circuit and the lower winding of the associated line relay to the upper winding of coil TTF until this allotting period is completed.

It will thus be seen that relay ST of the line finder associated with the first operated AL relay of the series (relay lAL in this example) will operate in response to the calling line condition, after which this AL relay will release to mark the link busy and will remain released until all links have been used again. When all links have been used over agin, relay RS is again operated for re-setting all the AL relays that have been released because the associated link became busy and are now in condition to be reoperated because the associated link has become idle. This operation provides uniform allotting, i. e., when the allotter is advanced to a particular step in its operation, the clearing out of a link in the rear of this step will not effect the allotting of this link in response to another call, but the allotting operation will be forced to go through to link #10 (last link) before it can come back and use the earlier cleared link.

In the event that the finder switch fails to stop on the marked level or on the marked contact in the level, it will advance to the overflow position for closing the overflow contacts illustrated in the lower portion of Fig. 3. This operation closes'a circuit for operating relay YS in the allotter which may be traced from break contacts in series of relays LS and AS, conductor 14, make contact of relay SA, lower winding of relay YS, resistor 17RS, conductor OF, make contact of the overflow springs XY OF and make contact of relay ST to it being understood that springs XYOF are closed in either the X or the Y overflow position. Relay YS eifects the re-.

lease of relay-SA, after which relays XA, XB, YA and YB and then YS are released, all in the previously described manner for clearing out the allotter circuits. The finder switch will be released because the circuit to relay ST of the line finder is opened when relay SA releases to disconnect potential from conductors 12 and IFST. The release circuit for the finder switch may be traced from break contact of relay ST, X or Y oif normal contacts and winding of release magnet Z to The time release feature of the allotter will now be explained. In the event that the calling line is not found and the allotter circuit cleared out within a predetermined time interval, in the previously described manner, the,

circuits will be automatically released by an impulse applied to the end of code pulse conductor 'ECP ap-.'

assets;

proximately 8 se,co'nds' after a preliminary pickup pulse is applied to pickup conductor PU. It will be observed that the pulse on conductor PU may occur at any time during the operating cycle of the allotter for extending this pulse through a make "contact of relay SA, conductor 21, break contact of relay TA, break contact and lower winding of relay LT to for operating this latter relay. Relay LT is locked operated over a circuit extending from make Contact of relay SA, conductor 22, break contact of relay TA, make contact and upper winding of relay LT and resistor 4R8 to it will nos. be assumed that the circuits are not cleared out during the 8 seconds following the pickup pulse, so that the pulse on conductor EC? is effective to close a circuit for operating relay LS which may be traced from conductor ECP, make contact of relay LT, break contact of relay LS, break contact of relay ES and winding of relay L8 to Relay LS bypasses the circuit through the contacts of the relay by way of the inner lower make contact of relay LS to its winding for locking this relay operated by the pulse on conductor ECP, it being understood that relay LS is released at the end of the impulse period on conductor ECP;

A circuit is now closed for operating finder failure relay FF which may be traced from make contact of relay IAL, break contact of relay AS, make contact of relay LS, break contact and winding of relay FF to Relay FF closes a locking circuit for itself extending from break contactof locking key LK, make contact and winding of relay FF to Relay FF closes an obvious circuit for lighting lamp FNF as an indication to the attendant that some finder failed in its operation. This relay and lamp are maintained, energized until manually released by, the momentary operation of key The operation of relay LS also stops the pulse generating relays by opening up conductor 13. Relay AS is also operated over a circuit extending from make contact of relay LS, make contact of relay FF, resistor 5R8 and winding of relay. AS to This relay locks itself operated over a circuit extending from make contact of relay lAL, make contact of relay AS, resistor 6R8, resistor 5R5 and windingof relay AS to The operation of relay LS also effects the release of relay SA by de-energizing conductors 11 and 17 Relay SA is slightly slow to release because its winding is bridged by resistor EKG and after this relay releases a circuit is closed for operating relay ES extending from break contact of relay SA, conductor 23, make contact of relay LS and upper winding of relay ES to Relay ES closes a locking circuit for itself extending from makecontact of relay ST, conductor 25, make contact and lower winding of relay ES to The release of relay SA opens up the above described operating and locking circuits for relay LT for efiecting the release of this relay.

The finder is released because relay SA, in releasing, disconnects potential from conductors 12 and lFST for effecting the release of the ST relay of the finder which in turn releases the finder switch in the previously described manner. Relay lAL is released because its lower winding, including conductor lALG, is opened by the release, of relay ST and not closed again until the switch reaches normalfor closing the normal contacts of the- XON and YON spring combinations. As an additional check on the release of relay IAL, the release of relay LS opens up the circuit of relay AS, but this relay is locked operated by way of resistor 6RS if the lAL relay does not release. Consequeutly, the upper winding of relay lAL is energized over a circuit extendingfrom break contact of relay LS, make contact of relay AS, make contact and upper winding of relaylAL to Since this energizationof the upper winding of relay lAL opposes that of itslowerwinding, the lAL relay is kicked down. The SA relay is now operated by way of conductor 11 to at a break contact of the LS relay. The ES relay is not released because of the previously de'-.

scribed circuit through its lower winding by way of corn ductor 25. Relay ES- remains operated until the call is cleared out by the next finder allotted and' the ST relay is released, because relay LS- will be released at this time.

If the allotter relay ST remains operated for an exceedingly long period of time, due to the fact that the second allotted link in the above example fails to clear out the allotter circuit, pulses on conductors TF1 and TF2 are efiective to bring in an emergency start finder alarm lamp ESP as will now be described. With relay ST operated, a pulse on common pulse conductor TF1 operates relay TA by way of conductor 24 and this relay locks operated over a circuit extending from make contact of relay ST, conductor 25, make contact and wind ing of relayTA. to The operation of relay TA opens up and releases relay LT, it operated at this time. After a comparatively long' interval of time, a pulse is applied to conductor TP2 and, if relay ST has not been released for releasing relay TA, a circuit is extended from conductor TF2, make contact of relay TA, break contact of relay ES, break contact and winding of relay TB to for operating this latter relay. Relay TB locks operated to on conductor 25. Relay TB remains locked as long as the ST relay is operated and lamp ESF is energized over acircuit extending from make contact of relay TB (or TA), break (or make) contact of relay ESP and lamp ESF to It will be understood that the circuit of lamp ES may control a major alarm for indicating to a distant operator that there is a major trouble condition in this remote dial ofiice.

It will now be explained how relays CB and RD of the selector are operated. Referring back to the time that relay ST of the line findcr was operated, a preimpulse is applied to the line conductors TT and TR leading to the selector for operating relay CB of this switch. This circuit may be traced from break contact of the X and Y 'overflow spring combination of the selector (Fig. 5) ZXYOF, break of relay XD, upper winding of relay CB, break contact of relay SW, conductor TT, make contact of relay ST, resistor 8R8, break contact of relay SW of the finder, conductor TR, break contact of relay SW of. the selector and lower winding of relay CB to The operation of relay CB closes a circuit for operating relay RD extending from break contact of relay SW, make contact of relay CB and winding of relay RD to 'By means of this pre-impulse circuit the CB and RD relays of the selector are operated well in advance of the association of the selector link with thecalling line for providing the above mentioned control by on conductor TS which is applied at the selector through a break contact of relay PT and make contact of relay RD to conductor TS. The operation of relay SW of the line findersubstitutes the closed calling line circuit for the above mentioned pre-impulse circuit for holding the CB and RD relays of the selector in "their operated'positions.

Although the first selector and connector operations will later be described in detail, it will now be pointed out how the line and line finder circuits are released when the calling party terminates the connection. Hanging up the receiver atthe calling station'opens up the calling line circuit for releasing relay CB of the selector or the connector (if the call has progressed through to the-connector'), the release of relay CB of the selector orconneetor effects the releaseo'f the associated R'D relay for removing potential from the sleeve conductor, including conductor TS of Fig. 3. Thisopens up and releases relays SW'a'nd ST of th'e'line finder, as well as releasing relays CO and LO of the line circuitbecause (-l) is removed from conductor 3 extending back through linetfinder wiper PS to the calling line.

. When relay LS of theallotter is operated in response to a finder failure condition, a'circuit'is closed for energizing the all trunks busy conductor ATB extending from (+),'make conta'ct-of relay: LS,.-conductor 27, make contact of relay RS and conductor ATB. Sincethis circuit is effective if relay LS is operated, the number of finder failure operations may be counted by a meter on conductor ATB.

It will be noted that there is a circuit normally extending from sleeve conductor TS of Fig. 3 to the upper winding of relay SW. This is for the purpose of making a finder-selector link busy by means of the usual test jack arrangement associated with the link. This is accomplished by applying potential to conductor TS at the test jack for energizing and operating relay SW. The operation of relay SW disconnects the associated AL and ALG conductors for effecting the release of the AL relay associated with this link. This makes the link busy in the manner previously pointed out.

Selector operation The operation of the selector shown in Fig. 5 will now be explained. When the calling line is extended to conductors TT and TR leading to the selector, by the operation of relay SW of the finder, relay CB is held operated over the previously described circuit. Relay CB closes a circuit for operating relay RD extending from break contact of relay SW, make contact of relay CB and winding of relay RD to A circuit is now closed for operating relay XD extending from break contact of relay HA, makecontact of relay RD, break contact of X oil normal spring combination IXON and lower winding of relay XD to The operation of relay XD switches, at its uppermost continuity spring combination, the tip side of the calling line from to the common dial tone circuit, it being understood that the common dial tone conductor extends through a dial tone transformer or the like to Relay SW of the selector is primed by the operation of relay RD closing a circuit from break contact of relay SW, make contact of relay CB, resistor HRS and upper winding of relay SWto this priming circuit being for the purpose of rendering relay SW fast operating when the switch through circuit is completed as will be later described. Relay RD also applies to sleeve conduc tor TS for holding relays ST and SW of the line finder and for extending this back over conductor 3 for holding the cut oil and lockout relays of the line circuit. This circuit was previously traced.

It will now be assumed that the calling party dials 2 for the first digit, resulting in the transmission of two impulses by the release of relay CB once for each im pulse transmitted, after which this relay remains energized. The first release of relay CB closes a circuit for operating pulse assist relay HA extending from break contact of relay SW of the selector, break contact of relay CB, make contact of relay RD, make contact of relay XD, upper winding of relay HA and its break contact to The operation of relay HA is extremely fast because the circuit is to direct at its break contact. After the operation of relay vHA, this direct is removed and the relay must then remain operated in series with resistor 12RS, thus rendering the relayv fast to release because of the reduced holding current provided by the insertion of resistor IZRS. The operation of relay HA closes a locking circuit for itself extending from break contact of relay PT, make contact of relay RD, make contact of relay XD, make contact of relay HA, break contacts in series of magnets X and Y, upper winding of relay HA and resistor 12RS to This (l-) also operates magnet X over a circuit extending through another make contact of relay HA and make contact of relay XD through the winding of magnet X to at a break contact of release magnet Z. The operation of magnet X opens up its break contact for de-energizing the upper winding of relay HA,

the switch is stepped to its first level.

thus making the continued operation of this relay dependent upon the pulse provided at the break contact of relay CB. It will thus be seen that relay HA provides the pulse for operating magnet X and also locks itself in its operated position until magnet X actually operates. When relay CB energizes at the termination of the impulse, relay HA is released and the circuit to magnet X is opened for efiecting the release of this magnet, thus The operation of relay CB at the end of the first impulse opens up the previously described operating circuit of relay HA so that this relay is released for de-energizing magnet X.

When relay CBreleases to mark the beginning of the second impulse, relay HA is operated and looked as before and magnet X is operated for opening up the locking circuit of relay HA. When relay CB operates to mark the end of the second impulse, relay HA releases for eifecting the release of magnet X, thus the switch is advanced to the second level. Since it is assumed that only two impulses are transmitted for this digit, relay XD will now be released as an indication that selection of the idle terminal in the selected level is to be effected. Although the stepping of the selector switch away from its normal position opens up the lower winding of relay XD, this relay is maintained in its energized position during the transmission of impulses by means of a circuit including its upper winding which is connected in multiple with' magnet X, it being understood that relay XD 'remains operated during impulsing because of its slow acting characteristics. When relay XD releases at the end of the impulse transmission, the dial tone common is disconnected from the calling line and the line circuit is reconnected to at the overflow contact ZXYOF.

The release of relay XD closes a circuit for operating relay HA extending from break contact of relay:

PT, make contact of relay RD, break contact of relay XD, XX wiper and associated terminal, conductor M, contact 2YON in its normal position, upper winding of relay HA and its break contact to Relay HA is locked by way of a circuit extending from break contact of magnet Z, contact 2XON, make contact of.

relay HA, break contacts in series of magnets Y and X,

upper winding of relay HA and resistor .12RS to The (magnet is now operated over a circuit extending from this same and another make contact of relay HAfbreak contactof relay XD, winding of magnet Y and break contact of magnet Z to The operation of magnet Y opens up the above described-locking circuit for relay HA for effecting the release of this relay, which in turn opens up the above described circuit to magnet Y for tie-energizing this magnet with the switch wipers on the first terminal of the level.

Itwill be assumed that the first trunk in this level is busy in order to indicate how the test circuit functions. A busy trunk will have potential on the terminal to which wiper S of the selector is connected. This potential is now extended over wiper S, break contact of relay SW, make contact of relay RD, overflow contact 3XY OF, break contacts in series of magnets Y and X, upper winding of relay HA and its break contact to Relay HA again operates and closes its above described locking circuit and the above described operating circuit for magnet Y for causing the switch to advance to the second terminal in the selected level, after which magnet.

tacts in series of magnets Y and X, upper winding of re- Relay HA is m'ar- I ginal in its operation and will not operate in series with the lower winding of relay SW but the latter relay quickly. operates because of the above described circuit and becauseof the previously described priming circuit for this i lay HA and its break contact to.

A circuit is.

mean

relay. It will be observed that, as long as wiper S of the selector tests busy terminals, will be extended back over this wiper, break contact of relay SW and make contact of relay RD to the right hand terminal of the lower winding of relay SW for short circuiting this winding for preventing the operation of the SW relay until an idle trunk is reached.

Relay SW is maintained operated and conductor TS extending back to the finder is energized by means of the previously described circuit to through a break contact of relay PT and a make contact of relay RD until this latter relay releases, which is shortly after relay SW operates and opens up the circuit to the winding of relay RD. Before relay RD releases, comes back over conductor S from the switch ahead for locking relay SW operated by a substitute in place of the circuit to which is opened by the release of relay RD, this locking circuit for relay SW extending by way of its own make contact. The operation of relay SW opens up and releases relay CB, and as previously mentioned, before relay RD of the selector releases the CB and RD relays of the switch ahead are energized by means of the closed circuit across the calling line extended to the switch ahead by way of make contacts of relay SW and selector wipers T and R. This coming back over conductor S from the switch ahead, in addition to locking relay SW of the selector, is extended back by way of conductor TS for holding the finder and line circuit relays which are operated.

When the connection is released, relays CB and RD of the switch ahead will be released in a manner to be later described, thus removing from terminal and wiper S of the selector for opening up and releasing relay SW. A circuit is now closed for operating release magnet Z of this switch which may be traced from break contact of relay RD, break contact of relay SW, X and Y oil'- normal spring combinations in parallel and winding of magnet Z to When the Z magnet operates, a circuit is closed for operating relay HA which may be traced from make contact of magnet Z and lower winding of relay HA to The operation of relay HA in the selector at this time performs no function. When the switch reaches its normal position the circuit to magnet Z is opened by contacts 'SXON and 3YON for releasing this magnet and restoring the circuits to normal ready for another call. The removal of from conductor TS releases relays SW and ST of the line finder for closing a circuit which operates release magnet Z of the line finder, extending from break contact of relay ST, X and Y oil normal springs in multiple and winding of magnet Z to When the switch reaches nor mal, this circuit is opened by the off normal springs for effecting the release of magnet Z and the restoration of the circuit to normal.

It will now be explained how the selector operates when a number is dialed for the first digit which is to be cancelled. In this example it will be assumed that the first digit dialed is 8. When the selector is seized, relays CB, RD and XD operate and dial tone is applied to the calling line in the previously described manner. When relay CB responds to the impulses of the first digit, relay HA is operated, locked and magnet X is energized for advancing the selector to the eighth level, at which point relays HA and XD are released in the previously described manner. A circuit is now closed for operating relay HA extending from break contact of relay PT, make contact of relay RD, break contact of relay XD, XX wiper and its 8th level terminal, conductor W and lower winding of relay HA to This circuit from conductor W also extends through make contact of relay RD, break contact of relay SW and off normal contacts 3YON and 3XON to release magnet Z. Magnet Z operates and lOCnZS at its lower, inner make contact and releases the switch. When the switch reaches normal, magnet Z is opened for opening the circuit to the lower winding of relay HA and restoring the circuits to the same condition as when the selector was first seized. It will be understood that conductor W can be jumpered to any other terminal of the XX bank for digit cancelling on any other level.

It will now be explained how the time release feature of the selector operates. With relay CB operated, common pulse conductor TPl is extended through a break contact of relay PT and a make contact of relay CB to the winding of relay PT. When a short pulse is applied to conductor TF1, with the selector seized and not switched through, relay PT is operated and locked to by way of a make contact of relay CB and a break contact of relay SW. The operation of relay PT switches the holding circuit for conductor TS from to common hold conductor H2. Conductor H2 is connected to at the time conductor TPl is pulsed and for an appreciable time interval after the pulse on conductor TPl. If the selector is operated and switched through during this appreciable time interval, the connection is not released because the control potential then comes back over conductor S and wiper S from the switch ahead. However, if the selector is not operated and switched through within this appreciable time interval, potcntial is removed from common conductor H2 for de-ener gizing conductor TS and releasing the finder and line circuits. The release of the line circuit causes this particular line circuit to go to its locked out condition in the previously described manner. The disconnection of the line circuit from the CB relay of the selector, by the release of the SW relay of the finder, eifects the release of relays CB and RD of the selector for releasing this switch by means of a circuit extending from break contact of relay RD, break contact of relay SW, oif normal contacts.3YON or 3XON and winding of magnet Z to This restores the selector switch to normal ready for seizure by another call. The release of the selector from a completed connection is controlled by the removal of from sleeve conductor S and wiper S for de-energizing conductor TS, which effects the release of the finder and line circuits. The de-energization of conductor S also opens up the locking circuit for relay SW of the selector for closing the above described release circuit for magnet Z of the selector switch, thus restoring the selector circuit to normal.

Connector operation The connector of this system is of the universal type, that is, it will operate in a connector type system or a selector type system to provide the various features pointed out in the specification.

The terminals and reference characters, explained below, shown in the right hand portion of Figs. 12 and 13 and in the upper left hand portion of Fig. 11 are used to provide the various features required in the system when the connector is operating in a system which does not have selectors. In the present disclosure, a selector has been shown and described and the detailed operation of the connector will be described as operating in a system using selector switches. It will now be pointed out how the terminals shown in the right hand portion of Figs. 12 and 13 are connected when the connector shown in Figs. 613 operates in a connector type system, it being understood that none of the terminals A, B, C, D, G nor the XX bank, shown in the right hand portion of Fig. 12 are used in a selector type system.

When operating in a connector type system (no selectors), terminal A is connected to the XX bank level where the first digit causes codes l-lO to be rung on a called line.

When operating in a connector type system, terminal 13 is connected to the XX bank level where the first digit selects codes 11-20 for ringing on a called line.

When operating in a connector type system, terminalC is connected to the XX bank of the switching through" 13 level when the connector operates on a particular level (usually to provide the switching through feature.

When operating in a connector type system, terminal D is connected to the )Q( bank of the switching through level (usually 0) for restricting restricted lines (such restricted lines having connected on the HS lead of these lines) from this level.

Terminal G is connected to terminal G1 (lower right hand portion of Fig. 12) when the connector isvused in a connector type system.

Terminal H is connected to terminal H1 (upper left hand portion of Fig. 11) when the connector is used in a selector type system.

Terminal RV is connected to terminals 6-0 of the DE Wiper of the minor switch for controlling ringing on the ring side of the line for last digits l-5 and on the tip side of the line for last digits 6-0.

Terminal RV is connected to terminals 2, 4, 6, 8 and 0 of the DE wiper of the minor switch so that connection with odd terminals rings over the ring side of the line and with even terminals rings over the tip side of the line.

When the connector is seized by the selector, as previously described, the closed circuit across the calling line extended through the tip and ring wipers T and R of the selector operate relay CB of the connector over a circuit extending from break contact of'relay XD of Fig. 8, conductor 30, lower winding of relay CB, break contact of relay AB, break contact of relay DD, break contact of relay TD, conductor T, over the line and substation circuits in series, conductor R, break contact of relay TD, break contact of relay DD, break contact of relay AB and upper winding of relay CB to The operation of relay CB closes a circuit for operating relay RD extending from break contact of relay CA, conductor 50, break contact of relay TD, make contact of relay CB and winding of relay RD to The operation of relay CB also lights the monitor lamp connected to conductor MTR, this circuit extending from break contact of relay AB, make contact of relay CB, conductor 88, break contact of relay PT and common conductor MTR to the monitor lamp connected to this conductor.

When the connector is seized, the incoming HS conductor is extended to through the upper winding of relay TA for making a test to determine whether or not this relay should be operated, the circuit extending from upper winding of relay TA, conductor 115, break contact of relay AA, conductor 114, break contact of relay TA, conductor 100, break contact of X oif-normal contact lXON, break contact of Y off-normal contact IYON, con

ductor 105, break contact of relay TA, break contact of relay XD, conductor 51 and break contact of relay TD to conductor HS. It will be assumed that this is a local call (not a toll call), therefore the HS conductor incoming to the connector has no potential connected thereto, consequently relay TA is not operated.

The operation of relay RD closes a circuit for operating relay DD extending from make contact of relay RD and winding of relay DD to Relay DD closes a locking circuit for itself extending from make contact of relay RD, break contact of relay TD, make'contact and winding of relay DD to The operation of relay DD connects to master ground conductor MG, this energized conductor being used for controlling certain locking and releasing circuits as will be later described. Since relay DD is maintained operated as long as the connector is in use, it applies to common start conductor ST for operating the necessary common apparatus.

Resistor 13RS is connected between the master ground conductor and for spark absorbing purposes when the master ground conductor is de-energi'zed by the release of relay DD. The operation of relay RD also applied potential to the incoming sleeve conductor S for making this connector busy and for holding purposes, this circuit being traced from make contact of relay RD,

make contact of relay DD,break contact of relay TD,

conductor 62, break contact of relay 'BT and conductor S leading back to the preceding switch circuits. It will also. be noted that this same circuit, including conductor 62, is

connected to at a make contact of relay RD, this for a purpose to be later described in connection with areverting call.

Relay XD is now operated over a circuit extending from on conductor MG, break contact of X otf-normal' combination ZXON and upper winding of relay XD to In the event that this connector is used in a connector type system (no selectors provided) the calling party will now receive dial tone 'over a circuit extending from the common dial tone conductor, uppermost break cuit being traced from make contact of relay XD, break contact of relay TA, conductor 105, break contacts of the Y and X ofi-normal springs lYON and 1XON, conductor 100, break contact of relay TA, conductor 114,

break contact of relay AA and conductor to the right hand terminal of the upper winding of relay TA. Relay YD is operated at this time over a circuit extending from on conductor MG, break contact of relay DA, conductor '103, break contact of Y off-normal spring combination ZYON and lower winding of relay YD to The circuit for energizing the upper winding of relay XD is extended by way of conductor 73, jumper HH1 (used in a selector type system), conductor 97, break contact and lower winding of relay DA for energizing this relay. Relay DA operates and inserts the lower winding ofrelay DC in this circuit for operating relay DC. Relay PD is now operated over a circuit extending from break conductor MG, make contact of relay DC, make contact of relay PD, break contact of the minor switch off-normal spring combination ZMON and upper winding of relay PD to Relay PH is now operated over a circuit extending from make contact of relay PD, con

ductor 79, break contact of relay PT, conductor 80 and winding of relay PH to Relay DC is now locked over a circuit which may be traced from on conductor MG, make contact of relay PH, conductor 116, X make contact (closed first) of relay DC, conductor and upper winding of relay DC to ,Relay DA is now locked over a circuit extending from the on conductor 116, make contact of relay DA, conductor 121 and upper winding of relay DA to The circuits are now in condition for receiving the tens digit, it having been assumed that this digit is No. 2. Each arrangement, including relay HA, consequently, this relay will be operated in response to each release of relay CB, will lock itself operated and will repeat the impulse to the stepping magnet, the operation of the stepping magnet opening the locking circuit for the HA relay, this latter. relay being released only when its locking circuit is opened and when the CB relay operates at the end of the impulse.

This arrangement is effective to cause a sufiiciently longimpulse to be delivered to the stepping magnet to fully operate this magnet, even though the received impulse is of such short duration that the magnet would not be operated, although the impulse is sufliciently long to operate a fast acting relay. Relay HA is made very fast to 

